cooling question

[fastrthnstock]

i just removed thermostat and cylinder temp sensor and wow inside looks a mess, some sort of corrosion build up. is there anything it can be flushed or cleaned out with?

 

[rubinjames]

Re: cooling question

Scale from the water you run in. Might have to have engine taken apart and cleaned out if real bad.

 

[Yamajoe]

Re: cooling question

This scalely buildup will also be throughout your water jacket in the cylinder head, if it is bad, consider removing cylinder head and cleaning.